Refrigeration



m 1942- P. P. STRANDBERG 2,284,691

REFRIGERATION Filed March 30, 1940 2 Sheets-Sheet l W L z/ 25 INVENTOR.

BY: I PM, W W Wham MATTORNEY.

J1me P. P. STRANDBERG 2,284,691

REFRIGERATION Filed March so, 1940 2 Sheets-Sheet 2 f6 if.

Patented June 2 19 42 PAT YOFF

a REFRIGERATION I I n Per Paul Strandbeig, Stockholm, Sweden; asv signor to Platen-Munters Refrigerating Sys-j tem, Aktiebolag, Sto

ration of Sweden Application ckholm, Sweden, a corpo- .In ce ent April 14, 1939' 15 claims;

This invention relates to rerrigerationg more particularly to a refrigeration-system. emfbodying evaporation of refrigerant, ;iluid;in,the

presence of an inert gas;

iary circuit for inert gas into which-retrigerant fluid isvaporized from weak absorption liquid flowing framennle e iixemrvsxiiu siqete amassof absorption, andproviding a placeofcondensation in such auxiliary circuit inuwhich vaporized refrigerant fluid isliquefiedv liquid refrigerant formed in the place ofcondensationl-in the auxiliary circuit may'be condu'cted toIa -place of evaporation to produce a usefuljref'rigerating of feet. Further, the heat of condensation and also I the heat of .rectifieation or] vapors, flowing" from the place of vaponjexpulsion is evaporation of refrigerant? ;flu gas frommeak absorption liquid.

The invention, to gethe other objects and advantages thereof, wlillwbe better understood upon referenceto the followlizedto effect ing description and, the accompanying drawings s th mo e i "with thelabove and forminga part of thisspec'if cation, and of which;

Fig. 1 illustrates more orjiless diagrammatically a refrigeration system embodying the invention;

ojf. -the' Fig. '2 illustrates another embodiment invention shown in Fig. 1; v =4 l Fig. 3 illustrates more or less diagrammatically a refrigeration system similar to Figj 1 and in which are included additionalelementsnot shown in Fig. 13" and 3 rigyfi illustrates still hi hs embodiment 1.5:

the invention shown; in Figs. 1 to" 3' in elusive.

InFigQl the invention is embodied'in anabsorption refrigeration system of a uniform pressure type containing an auxiliary agentorpressure equalizing gas.

i The circulation of gasin the Q .371. 5 .y w t solution and flows througha conduit I 6 into condenser I.

In condenser lithe. expelled vapors are conjdensed, as'will vbe describedpresently, and the 7 liquid condensate flows through a conduit l'l into the upoer-fp'artof evaporator I! which may be arranged inathermallyinsulatedspace l8. Liquld refrigerant in evaporator lz evaporates and di-fluses intoflinertflgas which enters through a ondui-t I 9, thereby producing a'refrigerating efreawitheonsequent absorption ofr heat from the {surroundings V The rich gas mixture of refrigerant vapor and inertlgas formed inevaporator; I2 flows fromthe lower part thereof through an inner conduit drs'gas heat'excliangerffl, a conduit 2|, and vessel 22 into the lower end of absorber I3. The absorber :l3is diagrammatically shown in the form 'of' a looped coil' havinga plurality of fins 2ll secured thereto for air-cooling. V

In absorber l3 the-[rich gas mixture flows counter-current to downwardly flowing weak absorption liquid which enters througha conduit 24. ""The absorption liquid absorbsrefrigerant vapor. from'theinert gas and inert gas weak in refrigerant vapor flows from absorber l3 through a conduit 24', outer passage 25 of gas heat exchanger 21, and conduit I9 intothe upper part of evaporator l2. v

v as circuit ins cludingevaporator l2 and. absorber, I3 is due to the difference in specific weight ofthe columns of gas rich'and weak, respectively, in refrigerant vapor; Since the; richjga-s is heavier than the weak gas, force is produced or developed within the systemfor causing flow of rich gas to abysorber l3 and flow of weak gas totheevaporator i0 f l J3 into the vesselfl. From vessel enriched absorption liquid flows through an inner pas- Such a system includes a generator Ill, condenserlil, evaporator I2, and

absorberlil. The system containsa solution of refrigerant in absorption liquid, such as ammonia in water, forexample, and also anauxiliary agent 2 or inert gas, such as hydrogen. The generator I0 is heated in any suitable mannenas by a gas burner l4, for example, which projects its flame into the lower end of a flue l5. By heatinggenerator l0, refrigerant vapor is expelled out of upper part of generator l0. Refriger Enriched absorption liquid flows from absorber sage 26 of a liquid heat exchanger 21 and an inner passage 280i a liquid heat-exchanger 29 to a coil 30 which is disposed aboutthe lower end ,of fluel5. ..Liquid is raised by vapor-liquid lift action from ccilt30jthrough a-tubeggl into the expelled out of solution in generator-llhftogether with refrigerant vapor entering through tube 3|,

"flows through conduit I6 into. condenser II, as

explained above.

The weakened absorptionliquid from which refrigerant has been expelled flows through a conduit 32, outer passage 33 of liquid heat exchanger l9, conduit 34, a vessel 35 in thermalexchange relation with condenser H, conduit 39, outer passage 31 of liquid heat exchanger 21, and conduit 24 into the upper part of absorber l3. The circulation of absorption liquid in the circuit just described takes place by gravity. action and is effected by the raisingrof nquidflli tube n by vaporliquid lift action in generator ll.

The temperature in generator III is a gradient, the temperature being the highest in the lower part of the generator from which region weakened absorption liquid is conducted to vessel 33. In the vessel 35 the weakened absorption liquid flows in thermal exchange'relation with the gen.- erator vapors and further vaporization of refrigerant from weakened absorption liquid is effected at the condensation temperature of the refrigerant vapor flowing into condenser i I; that is, the latent heat of condensation resulting from condensation of refrigerant vapor in jacket or condenser I l is utilized to effect heating of weakened absorption liquid to expel refrigerantvapor I 'centration of refrigerant in solution is further lowered. This may be referred to as a stripping action, whereby the weakened absorption'solution is stripped of refrigerant and its ability to absorb refrigerant out of inert gas in absorber llisincreasedfl In the arrangement shown and forming an embodiment 'of the invention, not only is the heat resulting from condensation of refrigerant in condenser ll utilized to strip the weakened absorption solution of refrigerant in vaporizer 35, but also theheat of rectifloation is utilized to promote this stripping action. 1 The generator vapor usually is a mixture of refrigerant vapor and absorption liquid vapor, and, when ammonia and water are employed as the refrigerant andv solution entering vaporizer 35 is also utilized'to eifect evaporation of refrigerant fluid. Due to evaporation of refrigerant fluid, heat'of' liquid is abstracted from weakened absorption solution, thereby effecting cooling of the latter. With the temperature of the weakened absorption solution below the temperature of the generator vap'ors leaving the upper part of generator ill, the heat of condensation 'and' heat of rectification are transferred to weakened absorption solution in vaporizer 35.

By making the weak absorption liquid weaker with the so-called stripping action provided, a lower refrigeration temperature is obtained. The evaporating temperature of refrigerant fluid in evaporator" is a function of the partial pressure of refrigerant vapor. The more effectively refrigerant vapor is absorbed from inert gas in absorber l3, the less refrigerant vapor will be contained in the inert gas entering evaporefrigerant vapor in the inert gas introduced into evaporator II, the partial pressure of refrigerant "vapor in such gas will be less, whereby evaporation of refrigerant fluid will be effected at a lower temperature.

In order to recover and effectively use the refrigerantexpelled from weakened absorption liquid in vaporizer 35, the vaporizer is arranged to form a part of an auxiliary circuit for inert right-hand end of vaporizer 35 and by a conduit ll to' evaporator l2. The auxiliary gas circuit including vaporizer 35, condenser 39 and connect- "ing conduits 38 and 40 contains an inert gas, sucha's-hydrogen, for example, into which the refrigerant evaporates and diffuses in vaporizer 35. The mixture of refrigerant vapor and inert gas flows from vaporizer .35 into condenser 39 in which the refrigerant is condensed out of the inert gas, and inert gas weak in refrigerant returns fromcondnser 39 to vaporizer 35. This circulation of gas in the auxiliary gas circuit may be effected by the difference in speciflc weight of the columns of. gas rich and weak,

respectively, in refrigerant vapor. The liquid refrigerant formed in condenser 39 flows through conduit it into evaporator l2 whereby refrigerant fluid resulting from the so-called stripping action that takes place in vaporizer is effectively utilized to produce a useful refrigerating effect. The conduit 4| is shaped to form a liquid rator l2.

;If' desired, an arrangement may be provided wherebyliquid refrigerant substantially free of absorption liquid'may be introduced into evapora'torl2 from'condenser II. In such case the rator I2. By further reducing the amount of absorption liquid vapors may be removed from the generator vapors before the latter reach the condenser I I. This can be accomplished by providing in the conduit IS a rectifier of any type in any-suitablemanner, as by air cooling orby a cooling liquid, such as water, for example. As shown, condenser 39 is provided with a plurality of fins J2 forair cooling. The refrigeration system in Fig. 1 must be operated at'a temperature and with a concentration of refrigerant in absorption liquid which is dependent upon the temperature of the cooling medium. A condition for the correct operation of the system in Fig. 1 is that the generator vapors can be liquefied in condenser II at a temperature which issufficiently high so that the partial pressure of refrigerant in vaporizer 35, at the prevailing concentration of refrigerant in the weakened absorption liquid entering the latter from generator' III, will increase to such an extent that the vent flow of gas therethrough;

' weight of the columns of gas rich and weak, re-

tion of the system is being enacted; 7 Temperature of evaporae tor l2 Temperature of condenser 39 Temperature of generator lam +65 to '70" c.

shown in Fig. 1 are designated bathe same reference numerals. In this embodiment a second vaporizer I3 is provided in addition to thevaporizer 35. weakened absorption" liquid flows from the lower part ofgenerator it through conduit 32, outer passage 31 of liquid heat exchanger 2!, and conduit N to vaporizer It. From vaporizer 35 absorptionliquid flows through a conduit 44, outer passage ,5 of a liquid-heat exchanger 46, and conduit 41 to the second vessel or vapor- 48; the cutter passage 'IL-and conduit I l1. s i refrigerant flows:

porizer 43 through conduit. 31 of liquid heat exchange into the upper part of absor Absorption'liouid enriche from absorber l3 into vesscl'lfl, and thence from the latter throughthe inner passage 26 of liquid heat. exchanger 2T, inner passage 48' of liquid heat exchanger 16, and innerJpassage ll of liquid heat exchanger 29 into coil '30.

The left-hand end of vaporizer 35 is connected by a conduit "to one endf'of a jacket or condenser ill in thermal 'excharige relationwith the second vaporizerfl'n. The opposite end of jacket is connected by a conduit 52' to the right-hand end of vaporizer 3,5; The jacket. it is also connected by aconduit 51 to evaporator 12 and is formed to provide df-liquidtrap to pre- The left-hand end ofthe'second vaporizer I is connected by conduit 38 to the upper part of a condenser 39-, the lower part of which is connected by conduit 40'. to the right-hand end. of the second vaporizer l3 andalso by conduit ll to-the evaporator i2. F

In vaporizer-35 refrigerant vapori'zedout of weakened absorption liquid by" the heat of condensation and. heatoi rectification of generator vaporsflowing into condenser II; as in the embodiment shown in Figs. 1 and described above. The liquid refrigerant formed in condenser H flows through conduit H to evaporator II: The vaporizer 35, jacket orcondenser 51' and conduit connections 5' and 52' therebetween form an auxiliary circuit for inert gas, such as hydrogen, "for; example. The gas mixture of refrigerant vapor andinert gas flows from the vaporizer to the jacket orcondenserif in which refrigerant in condensed out of the inert gas, and inert gas weakl in refrigerant returns from the jacket or condenser il to the vaporizer 3;.- This circulation of inertgas through and between thevaporizer: 35 and jacket or condenser 5| may be effected by the difference in specific spectively, in refrigerant vapor Liquid refrigerant formed in condenser or jacket II flows through conduit to evaporator l2.

condenser 38 flows through conduit 4| into i'rigerant in Jacket or condenser ii. The vaporizer 43, condenser 1i and conduit connections II and I therebetween form another auxiliary circuit for inert gas. Iii-vaporizer 43 rerrigerant is vaporized out of weakenedabsorptionliquid into inert gas by the heat of condensationresuiting from condensation of refrigerantin jacket or condenser ii. The mixtureof refrigerant and inert gas formed in vaporizer I flows in this auxiliary circuit to" condenser 39 m which refrigerant is condensed out or the inert gas, andinert gas weak in refrigerant returns from condenser I! to the vaporizer 43 As in the auxiliary gas circuit just described, the circulation -of inert gas through and between the vaporizer l3 and condenser 19 may be effected by the difference in specific weight of the columns of gasrich and weak-,respectively, in refrigerant vapor. Liquid refrigerant formed in evaporator ll.

By utilizing the heat of condensation of vapors formed in vaporizer 35 toexpel refrigerant out of absorption solution in the second vaporizer N, a still greater utilization of the heat input into generator Ill is effected to strip the weakened absorption solution of refrigerant, so that the concentration of refrigerant in absorption solution entering absorber [3 will be at a minimum.- F-urther; all of the .additional refrigerantexpelledfrom the weakened absorption 'solutionis effectively recovered, whereby all of the expelled refrigerant may be utilized toproduce a useful refrigeratingeffect. When a number of condensation stages are employed like the condensation: stage formed by the auxiliary gas circuit; includingflvaporizer 35 and condenser iL'the" efflciency is improved for every condensation stage provided in that a, corresponding increase of pressure in the refrigeration system or a corresponding lowering of the condensation temperature of the condenser 39 is obtained. In

the embodiment justdescribed a corresponding change of the average concentration of the absorption'solution may be necessary-or desirable to maintain the desired conditions to insure proper operation of the refrigeration system. By way of example only and without limitation, the

following data is given to illustrate the conditions given in a refrigeration system like that shown in Fig. '2 in which proper operation of v the system is being effected.

Temperature of evaporator l2 0? C.

- Temperature of condenser 39; About C.

Temperature of vaporizer About +110 C. Temperature of vaporizerlL- About C.

Temperature of generator 10. Total pressure in the refrigerv ation system About 50 kg./cm.

In the use of the present invention a number About +130 C.

of condensation stages may be employed without undulyincreasing the size of the refrigeration system; This is so because only a slight difference in temperature between each condenser and its associatedvaporizer ls-suflicient to effect complete transfer. of the heat of condensation to the weakened absorption solution, even in instances where the heat transfer surface between the vaporizer and condenser is relatively small;

In vaporizer 43 refrigerant is evaporated out of weakened absorption liquid by the heat of In order tosimpl-ify the illustrated embodimerits of the invention shown in Figs. 1 and 2, the insulationabout certain parts of the system and certain vent connections have not been condensation resulting from condensation of reshown. The parts which preferably should be insulated are included within the areas definedby the dotted lines 54 in Figs. 1 and 2.

In Figs. 3 is illustrated an embodiment similar to those shown in Figs. 1 and 2 which includes 5 parts, such as certain vent connections and agas heat exchanger in an auxiliary gas circuit, not included in the embodiments previously described. The parts of the system in Fig. 3 similar to those shown in Figs. 1 and 2 are designated by the same reference numerals.

In Fig. 3 the auxiliary gas circuit includes a gas heat exchanger 55. As shown, the inner passage 56 of gas heat exchanger 55 is connected in a conduit 51 connecting the left-hand end of vaporiler-fl and the lower part of condenser 33. The outer pamage .58 of gas heat exchanger 55- is connected by a conduit 59 to the ,lighthand end of vaporizer; and by a conduit 60 to'the upper part of condenser 39. In the present embodiment the vapor spaces of the condenser Hand condenser 39 are in communication with the main gas circuit'including' the evaporator l2 and the absorber l3. This is accomplished by connecting the upper parts of Condensers II and 39 by ventconduits 60, SI, and 62 to the upper part of conduit 2| through which gas enriched in refrigerant news from evaporator I! to absorber l3. It is to b'' understood that it is contemplated that gas heat ex- 90 changer 55 and vent connections, like the conduits 50, BI, and 62 may be included in Figs. 1 and 2, and that these parts have been omitted from Figs. 1 and 2 for the purpose of showing features of the. invention more clearly. i

In order to eilfect precooling of liquid refriger-x ant flowing from condenser ii and 39 to"evaporator 12, the conduits l1 and 4| may be arranged in thermal exchange relation with gas heat exchanger 2!. The operation of the embodiment 40 shown in Fig, 3 is substantially the same as the embodiment shown in Fig. 1 and described above,- and hencethe operation of theembodirnent in Fig. 3 will not be repeated here.

.InYFig. 4 is illustrated anotherembodimentiof v I x-uid in said means.

the invention in which the parts similanto those in Fig. 3 are-designated by the same reference numerals. In this embodiment-the gasheat ex-, changer'55 is arranged at a. sufficiently high elevation and inclined downwardly toward the-.60 vaporizer 35, so that rectification of thefvapors flowing from vaporizer 35 to condenser 39 is effected. Liquid formed in the inner passage '56 of gas heat exchanger is conducted through conduit 51 to. vaporizer 35. In order to remove 55 any liquid which may collect in' the outer passage 58 of gas heat exchanger 55, a conduit 63' is 'connected to the. lower part of thispassage and to the vessel 22 below the liquid level therein. In other respects the embodiment in Fig.4 is'similar to Fig. 3 and further descriptionof-this embodi-- ment will not be given here. As in Figs. 1 and 2, w the parts within the areas defined by the dotted lines 54 in Figs. 3'and 4 indicate the parts of the refrigeration system which are s'ulateda It has'already been pointed out that absorption liquid as well as refrigerant liquid flows through preferably in- 65 conduit I"! from condenser -II to evaporator I2.

. primarily employed to effect cooling of space I8. Liquid refrigerant substantially free of absorption liquid flows from condenser 39 to evaporator pointed out in the following-claims.

Whatds claimed is:

- well known in the art. The sequence in which liquid refrigerant is introduced into evaporator 12 from the different condensers is governed by the desired number'of temperature stages or temperature differences to be maintained in the evaporator. In certain instances, it may be desirable to provide means to accelerate the rate of gas circulation in the auxiliary gas -circuits;for example, as by increasing the en ma-crane columns of weakand rich gas, in order that the system will operate as near 33 190883118. .to the condensation point of the gas mixturert'o belid'u'ee fled.

-.-While several embodiments ofjthe invention have been shown and described. such variations and modifications are contemplated as fall within the true spirit andscope of the invention, as

1." An absorption refrigeration syitn includ- .in a generator,.means-to heat said generator to cause expulsion of refrigerant vapdri. from and thereby weaken absorption liquid therein, means for conducting weakened absorption liquid from said generator in the presence of inert ga to lower the vapor pressure of the refrig erantfiuid andthereby permit further expulsion of refrigf erant; vapor] from and 1 further "weakening of the absorption liquid, .and a condenser which receivesinertgas and refrigerant vapor from said means and in; whichthe refrigerant vapor is condensed toliquidf. f a

2. A system as in claim-'1 which also includes fl fa second condenser connected to receive refrig erant vapor from said generator and arrangedin heat transfer relation to said means'so that heat of "condensation is transferred to absorption liq- 3. A system 'as in claim; 1 which also includes a second condenser'conhect'ed to receive vapor fromsaid generator, and an evaporator connected ;'to receive liquid from both said condensers. I (i. A systemas in claim 1 which also includes a second condenser connected to receive vapor fromsaid generator and arranged in heat transferrelation with said means, and an evaporator connected to receive liquid densers. v

from both said conceive, vapor from said generator, a first circuit for inert gas including an evaporator and an absorber, a'second circuit for inert gas including a second evaporator and a second condenser, a .cir-

' cuit for absorption liquid includinglsaid generator, absorber, and second evaporator, the latter being connected so that liquid flows .therethrough in path of flow from saidgenerator to said absorber and said first evaporator being con nected to receive liquid from said both .con-

densersl 6Q A system as in claim 5 in which said first condenser is arranged in heat transfer relation to said. second evaporator.

'7. A system as in claim 5 in which liquid in said. absorption liquid circuit flowing to and from said .secondevaporator is conducted in heat exchange relation with liquid in said circuit flowing from said absorber to said generator.

8. A system as in claim 5 in which said second circuit for inert gas including a second evaporator and a second condenser also includes a heat exchanger connected therebetween.

9. A system as in claim 5 in which said second circuit for inert gas including a second evaporator and a second condenser also includes a heat exchanger connected therebetween, and a drain conduit for liquid condensate from said heat exchanger to said absorption liquid circuit.

10. A systcrn' as in claim 5 which also includes a vent connection from both said condensers to said first circuit for inert gas.

nected to deliver liquid to said evaporator, and

' another circuit for inert gas including said second vaporizer and a third condenser, the latter also being "connected to deliver liquid to said i 11.: An absorption refrigeration system includ- 1 ing a generator, a first circuit for inert gas'including an evaporator and an absorber, acircuit for absorption liquid including said absorber and said g'enerator and a plurality of vaporizers through which absorption liquitl flows, in its path of flow from saidgenerator to said absorber, a

condenser in heat transfer relation with the first of said Vaporizers and connected to receive vapor from said generator and d liver liquid to said evaporator, a second circuit or inert gas including said first vaporizer and a second condenser, the latter being arranged heat transfer relation with 'a second of saidvaporizers and'conevaporator.

12. A system as set forth in claim 11 in which the liquid flowing to and from said Vaporizers is conducted in heat exchange relation with liquid flowing from said absorber to said generator.

13. A method of refrigeration which includes heating absorption liquid to expel refrigerant vapor therefrom, thereby weakening the absorption liquid, conducting the weakened absorption liquid into the presence of inert gas to cause further expulsion of refrigerant vapor therefrom, the latter diffusing into the gas, and condensing the vapor to liquid to cause separation of the refrigerant from the gas.

14. A method as in claim 13 which also includes liquefying vapor formed in the first expulsion step by heat transfer to absorption liquid in said further expulsion step.

15. A method as in claim 13 which also includes condensing to liquid refrigerant vapor formed in said first expulsion step, and evaporating in the presence of inert gas the liquidformed by both condensing steps.

' PER PAUL S'I'RANDBERG. 

